Sonic boom signals are produced by the nonlinear propagation of shock waves and pressure disturbances generated by supersonically traveling aircraft, missiles, artillery projectiles, etc. The annoyance and startle caused by these impulsive, high amplitude sound signals has hampered previous attempts at the development of civil supersonic transport aircraft. For example, the Anglo-French Concorde was not allowed to fly supersonically over land, because of the unacceptable public response to the high amplitude sonic boom signals it generated.
In spite of the challenges presented by the sonic boom phenomenon, supersonic cruise flight remains a goal for many in the aerospace industry who have concluded that business jets with supersonic cruise capabilities are technically feasible. However, supersonic flight over land may be required for a supersonic business jet to be profitable. Therefore, the sonic boom signals must be “minimized” in order to reduce or eliminate public annoyance. Some means of quantifying the “loudness,” “noisiness” or “intensity” of a sonic boom signal will be required in order to determine what signals, and therefore what type of supersonic cruise aircraft, will be acceptable for supersonic overland flight.
Most contemporary sonic boom prediction tools approximate the strong compressions in a sonic boom signal as zero-thickness shock waves. The relative motion and coalescence of these shock waves are governed by the Rankine-Hugoniot relations of gas dynamics. These zero-thickness shocks do not directly allow for the calculation of noise metrics, because spectral analysis cannot be performed.